DNV Confirms Energy Efficiency Gains for LNG Carries with DFE+ Propulsion
New Dual Fuel, Electric+ (DFE+) concept, developed by ABB and MAN Energy Solutions, has been recognized by DNV as a more energy efficient alternative to current conventional designs for liquefied natural gas (LNG) carriers.
DNV has quantified the gains that owners of LNG carriers could expect to achieve using the new DFE+ solution and found that it could help LNG carriers boost energy efficiency by up to 7.5%, therefore enabling greater emissions reduction.
The number takes into account the smaller machinery space requirements with ‘a conservative estimate’ of 5% greater cargo capacity, which contribute to the ship’s increased transport work.
Comprising MAN’s four-stroke 49/60DF dual fuel engine and ABB’s Dynamic AC power distribution and control system, the solution has been developed to overcome efficiency challenges that are specific to the vessel type.
DNV’s Maritime Advisory assessment concludes that the DFE+ concept is ‘a competitive and more energy efficient alternative to even the most efficient conventional dual-fuel LNG carrier propulsion designs.’
From January 1, 2023 the International Maritime Organization (IMO) has required shipowners to report vessels into an Energy Efficiency Design Index (EEDI), an Energy Efficiency Existing Ships Index (EEXI) and an operational Carbon Intensity Index (CII).
These tools benchmark ships so that owners know what they must do to meet IMO targets for reducing greenhouse gas emissions.
As the newest addition to MAN’s four-stroke portfolio, the MAN 49/60DF engine is optimized for LNG. It is also highly compatible with ABB’s Dynamic AC system, which combines the merits of conventional AC with those of variable frequency to allow the engines to operate on optimal speeds – significantly improving total fuel consumption.
"Owners of LNG carriers face specific challenges in complying with the regulations, given their reliance on propulsion solutions with limited potential for efficiency gains. The ABB – MAN propulsion concept aims to offer a highly effective way for LNG carriers to meet progressively tightening emissions regulations while also reducing fuel costs,” said Prof. George Dimopoulos, Scientific Advisor, DNV.
“With the current global orderbook for LNG carriers including more than 200 vessels, and emission regulations continuing to tighten, owners need new technologies to meet the requirements that apply to this specific class of ships.
“DNV’s testimony on the gains available to LNG Carriers with the new solution developed by ABB and MAN Energy Solutions proves the time is right to explore the next-generation technologies for this vessel type,” added Rune Lysebo, Strategic Market Development, ABB Marine & Ports.
DFE+ could be installed with an energy storage solution to operate as a spinning reserve or come coupled with ABB’s Azipod electric propulsion. ABB and MAN said they would also explore integrating fuel cells as the technology matures.